Bronchoalveolar Carcinoma Grading in Dogs
Canine bronchoalveolar carcinoma (BAC) is a cancer that originates in the lungs of dogs. It can occur in any breed and at any age, though it is rare—these lung tumors account for only 1 percent of all canine tumors, according to the Veterinary Society of Surgical Oncology. Standardized grading and staging systems describe the aggressiveness, or rate of growth, and the spread, or metastasis, of cancers and help veterinarians and their clients determine treatment options and predict results.
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Facts
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In a March 1, 2008, "DVM360" online article, Drs. Kerry Rissetto, Pamela Lucas and Timothy Fan noted that dogs do not usually display symptoms in early stages of BAC, other than general ones like fatigue or weight loss. A persistent nonproductive cough may lead to the discovery, but usually only until the cancer is advanced.
Chest X-rays and examining some of the tumor's cells provide information on how fast the cancer is growing and how far it has already spread. The findings, expressed as grading and staging, help in predicting how well your dog will respond to treatment.
Grading Versus Staging
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Grading describes how fast the tumor is likely to grow, based on a pathologist's examination of the cells' appearance in a tissue sample taken from your dog. Pathologists are veterinarians with special training in reading test results.
Staging, done by your dog's primary veterinarian or surgeon, classifies findings about the size, number and location of tumors, lymph node involvement and whether the cancer has spread to other parts of the body.
When combined, the grade and stage of the cancer offer insight into what treatment to pursue and how successful it may be.
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Features
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Grading is done by taking a sample from the suspected tumor, staining it to make the cell structure clear, then examining it under a microscope. Pathologists classify cancers as grade I, grade II and grade III. As Dr. Daniel Degner explains on the Vet Surgery Central website, grade I tumors are considered less aggressive in terms of trying to spread to other areas of the body. Grade III cancer is considered the most likely to grow aggressively.
Considerations
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Grading standards allow pathologists to include subjective considerations based on their past experience, so results may not provide a probable outcome, because every patient responds differently, says Dr. Ingrid Pyka on the Pet Insurance website.
Your dog's general health and age must be factored into the treatment plan, as well as your willingness to subject the pet to possible discomfort, since the preferred treatment for BAC is surgical removal of the cancerous tissue or the entire lung, if necessary.
Significance of Grading
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The significance of a grading varies according to the type of cancer involved. Of dogs diagnosed with Grade 1 BAC, 50 percent lived at least 2 years after diagnosis. Since BAC is difficult to catch before it has reached an advanced stage and grade, Drs. Kerry Rissetto, Pamela Lucas and Timothy Fan suggest that concerned owners may ask for X-rays or CT scans, particularly for older pets, as part of a regular annual health checkup.
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References
Resources
- Photo Credit dog image by Trav from Fotolia.com
